This invention relates generally to digital magnetic tape drives and more specifically to an apparatus for automatically loading 8 mm magnetic tape cartridges into and unloading them from such tape drives.
Digital magnetic tape drives are used extensively in today's computing systems. Magnetic tape cartridges have recently become popular as storage units for use with these digital magnetic tape drives. In particular, 8 mm magnetic tape cartridges are being widely used because they are economical, compact in size, and effectively protect the tape medium from contamination that would otherwise result from dust and handling. Due to their standardized dimensions, magnetic tape cartridges lend themselves to use in automatic loading/unloading mechanisms.
A number of loading/unloading machines are known in the prior art for handling various types of magnetic storage media. For example, Datapath Technologies, Inc. provides desktop autoloaders to handle floppy disk media. Archive Corporation, Wangdat, Wangtech, and others provide autoloaders for use with 4 mm DAT data cartridges. IBM, Storage Technology Corporation, Fujitsu, and Hitachi, for example, provide autoloaders to handle 1/2" IBM 3480 type tape cartridges. Advanced Digital Information Corporation provides the ADIC LANbacker 4000/8000 for use with tape cassettes.
Exemplary of prior art autoloaders that handle 8 mm tape cartridges is the EXB-10, manufactured by Exabyte Corporation. This autoloader, for example, employs an elaborate pinch mechanism for grabbing and holding the cartridges as they are being loaded into or unloaded from an associated magnetic tape drive, or as they are being transported to and from storage locations. As a result of the complex servo controls and mechanisms that they employ, these autoloaders are quite expensive. In addition, operation of these prior art tape cartridge autoloaders is generally controlled by software programs installed in a host computer by modification of existing software programs. These software programs are disadvantageous because they consume valuable computer memory space and are difficult to modify.
It is therefore the principal object of the present invention t provide an autoloader for tape cartridges that operates simply, yet reliably, to load cartridges into and unload cartridges from an associated magnetic tape drive without altering any software programs stored in the host computer.
In accordance with one aspect of the present invention, a sensor is provided that is responsive to opening of the tape drive door for initiating operation of the autoloader mechanism.
In accordance with another aspect of the present invention, a hook is provided for the engagement of a tape cartridge during an unloading operation. The unloading mechanism advances the hook to engage the tape cartridge at an opening provided for the release of spool brakes but without the deactivation of those spool brakes.
In accordance with another aspect of the present invention, a retractable sleeve is provided to fit around a tape cartridge. While the hook is advanced to engage the cartridge seated in the tape drive, the sleeve is retracted into a position at the front of the drive poised to surround the cartridge. The hook pulls the cartridge into the sleeve during extraction of the cartridge from the tape drive.
In accordance with another aspect of the present invention, a lever is provided to retract the sleeve during the release phase of the unloading operation and thereby disengage the cartridge from the hook.
In accordance with another aspect of the present invention, a platform is provided for accepting a cartridge after it has been released from the hook. The platform is suspended on a spring that allows the platform to descend under the weight of a cartridge distance approximately equal to the width of the cartridge.
In accordance with another aspect of the present invention, tape cartridges are stacked sequentially in a vertical chute as they await loading into the tape drive. The cartridges ar constrained by the dimensions of the chute for stacking in a slanted position. A trap door is provided at the bottom of the chute to contain the cartridges stacked therein and to release the bottom cartridge of the stack at such time as it is to be loaded into the tape drive.
In accordance with another aspect of the present invention, a sliding cam operates the trap door and a spring loaded lever, in a predetermined sequence, to suspend the stack of cartridges above the bottom cartridge and opening the trap door, thereby permitting the bottom cartridge to slide into the open cartridge door of the tape drive. The return movement of the sliding cam then closes the trap door and releases the stack of cartridges, allowing them to drop until the bottom cartridge rests on the trap door.
In accordance with another aspect of the present invention, a lever and rotating cam are provided for closing the cartridge door of the tape drive, thereby completing an autoload cycle and initiating the internal operation of the tape drive.